Testing-transformer



E. P. LEE. TESTINGJRANSFORMER. APPLICKTFON FILED MAR-- 27.1919.

Patented Feb; 10,1920,

INVENTOR Hi5 ATTORNEY UNITED STATES PATE T OFFICE.

EARLE 1'. LEE, OF ROCHESTER, NEW YORK, ASSIGNOR TO NORTH EAST ELECTRIC COMPANY, OF ROCHESTER, NEW' YORK, A CORPORATION OF NEW YORK.

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" Specification of Letters Patent.

Patented Feb. 10,1920.

. Application filed March 27, 1919; Serial No. 285,497.

Y lowing to be a full,-clear, and exact descri tion of the invention, such as will enab e others skilled in the art to which it appertains to make and use the same.

' This invention relates to the devices used to test the armatures of dynamo-electric ma-' chines and commonly known as testingtransformers or growlers. 1 4

A testing-transformer, of the kind in question, always comprises a laminatedcore, generally of U-shape or equivalent form, of

which the polar extremities are cylindrically.

concave so as to conform to and partly embrace the armature which is to be tested,

The core is wound with coils through which an alternating current is passed.

I Since an exact fit is not essential, a testing-transformer of ordinary construction may be used with armatures differing slightly in diameter, but the permissible range of diameters is not great.

The object of the present invention is to increase the range of usefulness of a testingtransformer of given size, so that it may be used with armatures differing widely in diameter. To this end I rovide removable members 'or adapters, wh1ch cooperate with the polar extremities of the core of the transformer, and which are so formed as to permit operation upon an armature of a diameter substantially different from that for i which the polar extremities themselves are formed.

The preferred form of the invention is illustrated in the accompanying drawings, in which:

Fi re 1 is a side-elevation of a testingtran former, with adapters in place: Fig. 2 is a detail-view in side-elevation, on a larger scale than Fig. 1, showing particularly one polar extremity and the adapter in place thereon: and Fig. 3 is a view of the adapter alone, looking from right to left in Fig. 2.

The details of form and construction of the core, the windings thereon, and the means for supporting these parts, are of no consequence so far as the present invention is concerned. The invention is shown as embodied in a transformer of which the core 5 is U-shaped and is embraced by sideplates 7, which are clam ed' against the sides of the core by througholts 8. The core is energized by alternating current in coils 6,

which are inclosed -in housings formed in tegrally with the side-plates. The polar extremities of the core 5 are cylindrically concaved, 1n the usual manner, so as to 0on vform to the cylindrical surface of an armatare.

The adapters, vention particularly resides, are identical in form, each comprising a body 11 built up of thin laminae of soft iron or steel. These laminae are insulated from each other in any convenient manner, so that the alternating flux from the oore,may pass through the adapter without substantial loss from eddy currents. The laminae are secured together by rivets 12.

The adapter has two op osite cylindrical in which the present insurfaces, 9 and 1.3, the sur ace 9 being convex and conforming closely to the concave surface of the pole of the core 5. The concave surface 13 is curved about an axis parallel with that of the surface 9, but the radii of curvature are substantially different. In the illustrated form of the invention the radius of the surface 13 is the smaller, but this is not essential.

As shown in Fig. 1, an armature of the size indicated by the dot-and-dash line 10 may be tested when the transformer isused in the usual manner. When the adapters are in .place an armature of the size indicated by the line 16 may be tested. As shown inthe drawings the axes of curvature of the surfaces 9 and 13 are substantially coincident, but this is not essential: it is, however, convenient to have them parallel, in any case, since otherwise the laminae of which the adapter is made would be of different forms.

The adapter is placed'loosely on the core, so that it may be removed at once when a large-size armature is to be tested. In order to hold the adapter securely in place when in use, it is provided with integral lugs 14 and 15, formed by suitable projections on the laminae, which terminate the convex surface 9 and embrace the angles of the polar extremity. Since these lugs project slightly between the side-plates 7, they .guard against sliding movement of the adapter in every direction.

The invention claimed is: g

1. A testing-transformer having, in combination, a core of which the polar extremities are concavely shaped to conform to an armature of one diameter; and adapters, consisting of laminated magnetic material,

' surface. having convex surfaces shaped to fit against the concave polar extremities and concave of another diameter.

2. An adapter, for a testing-transformer, oomprislng a body, of laminated magnetic material, having opposite convex and concave surfaces, said surfaces being cylindrically curved about parallel'axes with different radii; and integral lugs projecting from the body at the extremities of the convex EARLE P. LEE. 

